This invention relates generally to the representation of irregular three-dimensional bodies and fields in a three-dimensional geographic information system. More specifically, this invention provides a method and a system for creating irregular three-dimensional polygonal models of oil and gas reservoir bodies or other three-dimensional volumes within a three-dimensional geographic information system.
Geographic information systems (GIS) are used in a very wide variety of applications in industries such as urban planning, agriculture, defense, utilities, oil and gas and the like. In virtually all GIS applications, the data and analysis performed on it are in two dimensions that typically represent coordinates on the surface of the earth. GIS technology is different from other computer-generated maps in that it allows for the existence and the access to the underlying informational database. For example, a GIS-generated map of the United States showing counties could be queried interactively to provide data on populations in counties, or income or any other variable tied to the underlying database that contained county-level information. In oil and gas applications, a two-dimensional GIS-generated map of oil fields would typically contain data on the reserves of the fields, number of wells, production levels, etc., all of which could be interactively queried by the user. GIS technology is also different from other computer-generated maps in that it has the ability to perform spatial analysis, the results of which are related to the location of mapped features and their attributes. For example, in a GIS-based xe2x80x9c911xe2x80x9d system, an operator receiving an emergency call enters the caller""s address and the GIS computes the closest fire station to the caller and the shortest-time route from that station to the caller. In oil and gas applications, an analysis could be performed that mapped all oil wells that produce over a certain volume of oil per day and are located within a specific distance of an identified oil pipeline. This type of application would help determine the long-run supply of oil from that pipeline.
In the oil and gas industry, the application of GIS technology to specific problems is typically accomplished by utilizing a generic GIS software platform, adding data to it and, in some instances, customizing the GIS software for the specific application. The GIS software platforms are purchased typically from one of the major developers such as Environmental Systems Research Institute, Inc. (ESRI) located in Redlands, Calif. that sells several types of GIS systems under the general names ArcInfo, ArcView and ArcGIS; MapInfo Corporation located in Troy, N.Y. that sells GIS systems under the general name of MapInfo; Intergraph Corporation located in Huntsville, Ala. that sells a family of GIS platforms under the general name GeoMedia; and the like. Data used in the system is typically either provided by the user or purchased from a geospatial data vendor or governmental agencies such as IHS Energy (Englewood, Colo.), PennWell Corporation (Tulsa, Okla.), A2D Technologies (Humble, Tex.), the US Geological Survey, the US Minerals Management Service, state geological surveys, and the like. Customization of the GIS platform to specific purposes can also be done by the users, contract GIS programmers, firms specializing in this work such as Earth Science Associates (Long Beach, Calif.) and the like. U.S. Pat. No. 6,012,016 (hereby expressly incorporated by reference in its entirety) typifies the process above in which a user has developed customized programming for a generic GIS platform (in their preferred embodiment, one of the products of ESRI) to manage and analyze oil well data obtained from a geospatial data vendor (in their preferred embodiment, Petroleum Information Corporation, now part of IHS Energy).
Most applications of GIS technology to date concern only features on the surface of the earth and provide two dimensions (identified by the latitude and longitude coordinates of location) to represent feature locations and to perform spatial operations on them. For example, in the oil and gas industry, features in two-dimensional GIS are represented by points (e.g., oil wells) and lines (e.g., oil pipelines) or polygons (e.g., the area of an oil field). While two-dimensional analysis is sufficient for some applications, three-dimensional analysis is preferred for various applications including, without limitations, oil and gas GIS applications because oil and gas fields are by their nature three-dimensional. Fields are not located on the surface of the earth, but thousands of feet below the surface. The accumulations of oil and gas at these depths occupy rock strata of a certain thickness, which may vary over the lateral (i.e., two-dimensional) extent of the field. Oil and gas wells are also three-dimensional, having trajectories that are only fully described by a series of triplets of observations that list the path of the well in latitude, longitude and depth below a datum (usually mean sea level). Accordingly, there is a need for three-dimensional GIS technology.
Existing three-dimensional GIS technology is limited and generally falls into two categories. The first category is representation of the three-dimensional topography of the earth""s surface in a GIS system, most commonly known as a digital terrain model. For example, both ESRI""s ArcView and ArcInfo GIS products have the capability of estimating an irregular surface from data sets of observations on the elevation of the earth""s surface at control points located by their latitude and longitude. That surface may then be introduced and manipulated within their generic GIS platforms. MapInfo""s MapInfo Professional GIS product allows viewing and manipulation of a digital terrain model within its system. U.S. Pat. No. 5,790,123 (hereby expressly incorporated by reference in its entirety) describes a method for generating terrain surfaces and lists its use within a GIS as an application. U.S. Pat. No. 6,229,546 (hereby expressly incorporated by reference in its entirety) describes a method and system for generation of terrain models, which may be assisted by the use of a GIS in the data management phase of the process. However, the output surface from the method, in a file format called VRML, would require modification for use within at least some commercial GIS platforms (e.g., ArcView), as VRML is not a valid input data format. Moreover, while generation of a three-dimensional surface and introduction of it into a three-dimensional GIS is an important innovation, such a surface is an irregular plane, not a three-dimensional volume. Such a surface, therefore, is geometrically insufficient to describe a three-dimensional volume such as an oil and gas reservoir, an aquifer, a defined volume of water within an ocean, sea or lake, a defined air mass within the atmosphere, and the like. Accordingly, there is a need to provide a three-dimensional GIS system that can create and manipulate a three-dimensional volume.
The second category of existing three-dimensional GIS technology is representation of man-made structures located on the earth""s surface, such as buildings. These applications typically take files generated by computer-aided design (CAD) software systems that provide the latitude, longitude and elevation of points sufficient to describe a structure (e.g., the locations of the corners of a base of the building and the top of a building). For example, in ESRI""s 3-D Analyst extension to ArcView, the GIS reads those coordinates and connects the control points to create virtual walls, floors and roofs to a building and correctly locates the building on the representation of the earth""s surface within a three-dimensional GIS scene. It is then possible to assign attributes to the three-dimensional model of the building so that it can be queried within the GIS and allows users to perform spatial operations on those three-dimensional features. In such an application, the model of the building built by the three-dimensional GIS system is an exact (if often simplified) representation of the geometry, as the dimensions and coordinates of buildings are exactly known from blueprint-type information typically produced by CAD software. For very simple geometric shapes (e.g., a building that is geometrically a simple box), the three-dimensional representation can be constructed by xe2x80x9cextrudingxe2x80x9d a rectangle representing the lateral extent of the building to an elevation representing the height of the building top above the surface of the ground (both ESRI and MapInfo systems do this). The ability to create three-dimensional features, such as buildings, constructed on exact boundary coordinates, and use them within a three-dimensional GIS is an important innovation. However, this method is not responsive to construction of three-dimensional features within a three-dimensional GIS where the boundaries are not exactly specified and/or are irregular.
Outside of GIS technology, there are computer methods for visualization of irregular three-dimensional features below the surface of the earth. For example, Schlumberger Information Services (Houston, Tex.) produces a suite of software products under the general name GeoFrame which includes a module called GeoVis that attempts to provide three-dimensional visualization of oil and gas reservoirs and other bodies of rock with specific properties. GeoVis relies on volume-cell (voxel) technology in which the volume of earth being modeled is divided into a very large number of three-dimensional cells. Each individual cell is assigned characteristic properties, based on the collection, processing and interpretation of seismic data over that volume of the earth""s crust. Cells can be classified based on characteristics of interest (e.g., specific seismic impedance, interpreted values of porosity, interpreted composition of interstitial fluid). Cells belonging to a class can then be xe2x80x9cturned-onxe2x80x9d or assigned a color so that they can be seen on the computer screen within a three-dimensional volume representing that portion of the earth""s crust. By assigning different colors to cells that possess common attributes (or the same range of attribute values), it is possible to see the geometric relationships between natural, irregular three-dimensional bodies within the volume of the earth""s crust under examination. Another example, is Landmark Graphics"" (Houston, Tex.) xe2x80x9cvolume interpretation systemxe2x80x9d called Earth Cube, which is very similar to GeoVis. Earth Cube input data comes principally from seismic data acquired throughout a volume of the earth""s crust and it represents sub-volumes of interest by attributes assigned to a very large number of cells into which the total volume is divided. U.S. Pat. No. 4,991,095 (hereby expressly incorporated by reference in its entirety) also describes a method for generation of three-dimensional computer models of irregular geologic features using the volume-cell approach. While the volume-cell approach to visualization of irregular three-dimensional features in the subsurface is an important method for visualization, these techniques are not part of GIS technology. Thus, they do not support GIS functionalities of relating unified features (as opposed to a collection of discrete cells with the same attribute values) to underlying databases. They also do not have the ability to perform the spatial analytic functions (e.g., query, legending, measurement, proximity, intersection, and the like) associated with GIS technology.
Accordingly, there is a need to provide a three-dimensional GIS system that can create and manipulate a three-dimensional irregular volume even if the boundaries of such volume are not specified.
The present invention fulfills these needs by providing a method and a system for constructing three-dimensional polygonal models of the three-dimensional irregular volumes (e.g., natural fields, natural bodies, and the like) for use in a GIS system. The present invention can create and manipulate models of these irregular three-dimensional volumes within the GIS platform even if the boundaries of such volumes are not completely specified in the input data. The irregular three-dimensional volume models constructed by the present invention can be associated with databases containing attribute data on the three-dimensional irregular volume being modeled and are also susceptible to spatial analytic techniques of GIS technology.
The present invention is particularly suitable for oil and gas reservoirs but can be used in various other applications such as concentrations of specific elements or compounds (e.g., metals, diamonds, and the like) in a specific three-dimensional irregular volume of the earth""s crust, aquifers (e.g., to represent volumes of rock occupied by water), quality of a specific volume of air or water over a geographical area, and the like. In contrast to the methods applied to construct representation of man-made objects, such as buildings, certain embodiments of the present invention do not require complete specification of the geometry of the feature being modeled, and the method is performed absent such information. In contrast to the visualization methods based on the voxel approach, the invention constructs unitary three-dimensional irregular volume models that can be associated with databases containing attributes on the modeled volumes and are susceptible to spatial analytic techniques of GIS technology.
The present invention produces a realistic depiction of natural fields or bodies such as the subsurface aspects of oil and gas field within a GIS platform. More preferably, the depiction""s employs a generic GIS platform. The present invention allows the user to visualize the geometric and attribute relationships between irregular three-dimensional bodies, such as oil and gas reservoirs, the wells and production equipment within them and rock sample observation points and surfaces constructed from them. Since the invention operates within a GIS platform, the present invention further contemplates performing one or more of a query, legending, measurement, proximity, intersection and other spatial analytic GIS operations.
In one aspect, the invention provides a method comprising: (1) introducing desired data including control points [e.g., geographic points of observations] and attributes relating to a three-dimensional irregular volume into a GIS platform; (2) estimating at least one two-dimensional polygon representing a lateral boundary of the three-dimensional irregular volume based upon values of a variable of interest at the control points; (3) estimating irregular surfaces representing top and bottom of the three-dimensional irregular volume by interpolating grids of depth values from the control points for the top and bottom surfaces of the three-dimensional irregular volume; (4) clipping the estimated irregular surfaces with the estimated at least one two-dimensional boundary polygon; (5) constructing multipatches of a network of triangular panels representing top surface, bottom surface, and sides of the three-dimensional irregular volume to produce a solid three-dimensional irregular volume model within the GIS platform; and (6) joining the attributes to the solid three-dimensional irregular volume model within the GIS platform.
In another aspect, the invention provides a method comprising: (1) introducing desired data including control points and attributes relating to a three-dimensional irregular volume into a GIS platform; (2) estimating at least one two-dimensional polygon representing a lateral boundary of the three-dimensional irregular volume based upon values of a variable of interest at the control points; (3) estimating irregular surfaces representing top and bottom of the three-dimensional irregular volume by interpolating grids of depth values from the control points for the top and bottom surfaces of the three-dimensional irregular volume; (4) clipping the estimated irregular surfaces with the estimated at least one two-dimensional boundary polygon; (5) constructing a grid of regularly spaced polylineZs representing top surface, bottom surface, and sides of the three-dimensional irregular volume to produce a wire frame three-dimensional irregular volume model within the GIS platform; and (6) joining the attributes to the wire frame three-dimensional irregular volume model within the GIS platform.
In another aspect, the invention provides a method that includes repeating the above-mentioned steps (for either solid or wire frame models) to create additional three-dimensional irregular volume models within the GIS platform. Finally, the method may optionally include adding features that are not created by the above-mentioned steps including, without limitations, two-dimensional structures, polylines, multipoints, grids, raster images, vector data such as that derived from well logs, potential field and seismic techniques, and the like.
In another aspect, the invention provides a method to create three-dimensional irregular volume model of an oil and gas reservoir within a GIS platform comprising: (1) collecting data on wells, reservoirs, fields and other features that will be included in the three-dimensional irregular volume model of the reservoir within the GIS platform; (2) loading desired software on to a computer system; (3) organizing the data on wells, reservoirs, fields and other features of interest into a database and the GIS platform; (4) estimating at least one two-dimensional polygon representing the lateral boundary of the reservoir;
(5) identifying the reservoir that is desired for creating the three-dimensional irregular volume model within the GIS platform; (6) estimating irregular surfaces representing the top and bottom of the reservoir based on the control points provided by wells that intersect the reservoir; (7) clipping the estimated irregular surfaces with the estimated at least one two-dimensional polygon representing the lateral boundary of the reservoir; (8) constructing multipatches to represent the top surface, bottom surface and sides of the reservoir to produce the solid volume three-dimensional irregular polygonal model of the reservoir within the GIS platform; (9) joining the attributes on the reservoir to the multipatch model of the reservoir within the GIS platform. This preferred embodiment may optionally include creating a wire frame model of reservoir by constructing a grid of regularly spaced polylineZs and/or its functional equivalent representing top surface, bottom surface, and sides of the reservoir to produce a wire frame three-dimensional irregular volume model of the reservoir within the GIS platform and joining the attribute data to the wire frame three-dimensional irregular volume model of the reservoir within the GIS platform. If the oil and gas field contains more than one reservoir, this preferred embodiment may also optionally include repeating the above-described steps to create either a solid and/or wire frame three-dimensional irregular volume model for each additional reservoir. Finally, this preferred embodiment may optionally include adding features that are not created by the above-mentioned steps for the creation of three-dimensional irregular volume model including, without limitations, two-dimensional structures, polylines, multipoints, grids, raster images, vector data such as that derived from well logs, potential field and seismic techniques, and the like.
In another aspect, the present invention provides a system comprising: (1) a computer system comprising of digital processor, working memory, data storage device, input means (e.g., mouse, keyboard, and the like), display monitor, and optionally, output means (e.g., printer and the like); (2) software that can be used to create a three-dimensional irregular volume model within a GIS platform using the above-described methods of the present invention, wherein data including control points and attributes relating to the three-dimensional irregular volume is stored in the data storage device and can be accessed by the computer system to create the three-dimensional irregular volume model with the GIS platform using the above-described methods of the present invention.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portion of the specifications and the drawings.